A mammalian helix-loop-helix factor structurally related to the product of Drosophila proneural gene atonal is a positive transcriptional regulator expressed in the developing nervous system.

We report the molecular characterization of a mouse basic helix-loop-helix factor, designated MATH-1, structurally related to the product of the Drosophila proneural gene atonal. MATH-1 mRNA is first detected in the cranial ganglions and the dorsal part of the central nervous system on embryonic day 9.5 (E9.5). From E10.5 onward, prominent expression of MATH-1 continues in the dorsal part of the central nervous system but becomes restricted to the external granular layer of the cerebellum by E18 and is undetectable in the adult nervous system. MATH-1 activates E box-dependent transcription in collaboration with E47, but the activity is completely antagonized by the negative regulator of neurogenesis HES-1. These results suggest that MATH-1 may be a target of HES-1 and play a role in the differentiation of subsets of neural cells by activating E box-dependent transcription.